Cancer is a cell tumor which is led to automatically mortal death, and causes a large percentage, that is apt to increase, of human deaths. Cancer cells are originally normal cells, and when the genes of normal cells are damaged by certain causes such as chemical substances, radiation or infection with virus and the like and the damaged DNA is not repaired, the accumulation of such DNA in the normal cell induces the normal cells to become cancerous. Generally, cells possess the functions for restoration of the damaged genes. If such systems are not working normally, irregular genes are accumulated. Various cancer-associated genes have already been found and there include cancer genes which accelerate cancer and cancer-inhibitory genes which suppress cancer.
It is known that the pre-cancer gene myc family is one family of such cancer-associated genes particularly related to cancer. Such family members are cell proliferation-associated genes which play an important role in cancer and ontogeny and the like, and abnormalities of myc gene have been found in human cancer at a very high ratio.
The cancer gene c-myc family consists mainly of three genes, c-myc, N-myc, and L-myc. Although the three genes exhibit distinct patterns of expression and timing, they appear to have basically the same biological activity. The expression of cancer gene c-myc is highly regulated at the level of transcription or after transcription and the like. Generally, the expression of c-myc is associated with cell proliferation and expression is reduced in the cell at interphase or during differentiation. Deregulated expression of myc family genes, through gene amplification, viral promoter insertion, chromosomal translocation, or promoter mutation is associated with neoplastic diseases in a wide range of vertebrates including humans (DePinho, R. A., et al.: (1991) Adv. Cancer Res. 57, 1-46; Marcu, K. B., et al.: (1992) Annu. Rev. Biochem. 61, 809-860; Morgenbesser, S. D., et al.: (1994) Semin. Cancer Biol. 5, 21-36; Henriksson, M., et al. (1996) Adv. Cancer Res. 68, 109-182; Grandori, C., et al.: (2000) Annu. Rev. Cell Dev. Biol. 16, 653-69). Embryonic mice with c-myc or N-myc deleted develop multi-organ hypoplasia and die during mid-embryogenesis (Stanton, B. R., et al.: (1992) Genes Dev. 6, 2235-2247; Sawai, S., et al.: (1993) Development 117, 1445-1455; Davis, A. C., et al.: (1993) Genes Dev. 7, 671-682). These results indicate that myc is the central regulator of cell growth (Henriksson, M., et al. (1996) Adv. Cancer Res. 68, 109-182; Grandori, C., et al.: (2000) Annu. Rev. Cell Dev. Biol. 16, 653-69; Lüscher, B.: (2001) Gene 277, 1-14).
These cancer genes, myc family genes encode the transcription factor (Myc protein) which regulates the expression of various genes (Grandori, C., et al.: (2000) Annu. Rev. Cell Dev. Biol. 16, 653-69; Lüscher, B.: (2001) Gene 277(October 17; (1-2):), 1-14). The protein encoded by myc family genes is a member of the basic helix-loop-helix leucine zipper (bHLHLZ) transcription factors. Dimerization of Myc protein with its obligate partner Max results in the formation of a heterodimer having sequence-specific DNA binding activity. The dimer binds to E-box sites (mainly CACGTG elements) through the basic part. The myc has another domain, the transcriptional activation domain and activates transcription of various genes by activities of these domains. Such Myc target genes (Dang, C. V. (1999) Mol. Cell. Biol. 19, 1-11) as ODC (Bello-Fernandez, C., et al.: (1993) Proc. Natl. Acad. Sci. USA 90, 7804-7808), cdc25A (Galaktionov, K., et al.: (1996) Nature 382, 511-517), RCC1 (Tsuneoka, M., et al.: (1997) Oncogene 14, 2301-2311), cyclin D2 (Bouchard, C., et al.: (2001) Genes & Dev. 15, 2042-2047), and Id2 (Lasorella, A., et al.: (2000) Nature 407, 592-598) have been identified. Attempts to identify genes capable of re-establishing normal proliferation by introducing an expression gene library to cells which the functional c-myc gene are completely lost have resulted in the repeated identification of c-myc and N-myc, other genes could not be identified. These results suggest that myc controls not a gene but genes to regulate cell proliferation. However, enough Myc target genes to elucidate the function of cancer gene myc have not been identified yet and therefore, the mechanism for demonstrating myc functions has not been satisfactorily clarified. Accordingly, the identification of the new genes expressed and regulated by myc can help elucidate the function of cancer gene myc.
Colon cancer is among the most frequent neoplasms in western countries. It is currently thought that most colon cancers develop from preexisting adenomas, although some may emerge de novo (Fearon E R, Vogelstein B: Cell 1990, 61:759-767; Kuramoto S, Oohara T: Cancer 1989, 64:950-955; Bedenne L., et al.: Cancer 1992, 69:883-888; Wada R, et al.: Cancer 1996, 77:44-50). Most colon cancers are known to progress through a gradual series of histological changes from normal state to premalignant (adenoma) and malignant stages (Fearon, E. R., Vogelstein, B.: ibid; Vogelstein, B., Kinzler, K. W.: Trends Genet 1993, 9: 138-141; Kinzler, K. W., Vogelstein, B.: Cell, 1996, 87: 159-170). In the course of cancer progress, it is considered that poorly differentiated (hereinafter referred to as “poor differentiation”) tumor generally progress faster than moderately differentiated (hereinafter referred to as “moderate differentiation”) tumor or more differentiated, namely well differentiated (hereinafter referred to as “well differentiation”) tumor.
Studies for elucidation of colon cancer-associated gene have shown that loss of function of tumor suppressor genes as well as activation and abnormal expression of oncogenes are responsible for carcinogenesis. It is reported that the proto-oncogene myc family, c-myc is overexpressed in most human colon cancers (Stewart, J., et al.: Br. J. Cancer 1986, 53: 1-6; Siroka, K., et al.: Cancer 1987, 59: 1289-1295) and most of which harbor mutations in the tumor suppressor adenomatous polyposis coli (APC) gene (Cottrell, S., et al.: Lancet 1992, 340: 626-630; Miyoshi, Y., et al.: Hum Mol Genet 1992, 1: 229-233; Powell, S. M., et al.: Nature 1992, 359: 235-237).
Recently, c-myc was specified as the target of the APC pathway and provided a molecular framework for understanding the overexpression of c-myc in colon cancers (He, T. C., et al.: Science 1998, 281: 1509-1512). This framework is supported by the observation that the expression of c-myc is either induced by loss of function of the APC gene or suppressed by the functional APC gene product.
In spite of intensive efforts to investigate the role(s) of c-myc in carcinogenesis, the mechanisms by which deregulation of c-myc gene expression contributes to carcinogenesis are still not fully resolved, and many aspects are still enigmatic (Lutz, W., et al.: Biochem Biophys Acta 2002, 1602: 61-71). c-myc gene is a multifunctional gene, and its functions include cell division, cell growth, and apoptosis. c-myc gene appears to control the expression of several genes that mediate each of the above functions, some of which may contribute to carcinogenesis. Functional information and expression patterns of novel genes controlled by c-myc gene may therefore contribute to a better understanding of carcinogenesis induced by c-myc gene.
In addition to colon cancers, esophageal cancer is one of the popular cancers in Japan. The number of patients drastically increases with aging. At present, the number of patients who die as a result of esophageal cancer is almost 3% of the total number of patients who die as a result of cancer. As the society population ages, it is expected that there will be more cases of esophageal cancer. Thus, esophageal cancer is an important disease in view of the health of nations.
The studies for elucidation of esophageal cancer-associated genes show that the loss of function of the tumor suppressor gene, the activation of tumor gene, and abnormality of expression are involved in carcinogenesis and the abnormal expression of c-myc has also been reported (Kennedy A R: Cancer Res. 1994, 54 (7 Suppl): 1999s-2005s).
The present inventors have searched genes which c-myc caused increased expression by a cDNA micro-array method. As a result, the novel cancer-associated gene of the present invention has been identified. c-Myc protein binds with the promoter sites which regulate the expression of the gene and makes the expression of this gene directly increase (Tsuneoka, M., et al.: J Biol Chem 2002, 277: 35450-35459). Leukemia cell line HL60 was treated with TPA (phorbol 2-myristate 13-acetate) to reduce expression of c-myc and prevent cell proliferation. Then, cell extracts of the leukemia cell line HL60 either treated or untreated with TPA were examined by a polyclonal antibody having a specificity to cancer-associated gene-encoding protein to confirm that the expression of the protein is reduced by TPA (Tsuneoka, M., et al: J Biol Chem 2002, 277: 35450-35459).
This protein was visualized by indirect immunofluorescence staining with specific antibody which indicated that it is localized in cellular nucleus. This protein has been named Mina53 and its gene has been named mina53 based on myc-induced nuclear antigen having 53 kDa of molecular weight.
Therefore, based on the knowledge by the above-mentioned arts, the present inventors believe that studies of the functional information and expression pattern of cancer-associated mina53 gene regulated by c-myc gene and its Mina53 protein using anti-Mina53 monoclonal antibody against Mina53 protein are useful for elucidation of carcinogenesis by c-myc gene.
The present inventors have made intensive research efforts to identify a Myc target gene in order to explain the function of c-myc cancer gene. As a result, they succeeded in producing anti-Mina53 monoclonal antibody against Mina53 protein (hereinafter referred to as “anti-Mina53 monoclonal antibody”). The present inventors have found that the expression of Mina53 protein in colon cancer cells is increased as compared to normal colon tissues by using anti-Mina53 monoclonal antibody, and further that the expression of Mina53 protein is an early event in colon cancer and specific character. The inventors have also found that Mina53 suggests the probability that plays a certain role in carcinogenesis of colon cancer. These results demonstrate that Mina53 protein can be used as a marker against, particularly, colon cancer and that there is a possibility to develop it as a target for the treatment of colon cancer diseases. Furthermore, it can also be used as a marker against esophageal cancer, and there is a possibility to develop it as a target for the treatment of esophageal cancer diseases. These have completed the present invention.